Background:The COVID-19 pandemic disrupted healthcare systems globally,raising concerns about delayed cancer diagnosis and treatment.In France,transurethral resection of bladder tumors(TURBT)was prioritized in nationa...Background:The COVID-19 pandemic disrupted healthcare systems globally,raising concerns about delayed cancer diagnosis and treatment.In France,transurethral resection of bladder tumors(TURBT)was prioritized in national urology guidelines to ensure the timely management of urothelial carcinoma.This study aimed to assess the impact of care reorganization on tumor staging,recurrence,palliative care,and mortality in bladder cancer patients from the pre-pandemic through late-pandemic periods.Methods:We conducted a retrospective multicenter study including all patients who underwent TURBT with histologically confirmed urothelial carcinoma between April and December of 2019(pre-pandemic),2020(early pandemic),2021(mid-pandemic),and 2022(late pandemic)in two French institutions.TURBT indications were categorized as diagnostic,palliative,or staging.Clinical and pathological data were compared across the four periods.Statistical analyses included Chi-square tests,Estimated Annual Percentage Change(EAPC),and multivariable logistic regression adjusted for age,sex,ASA score,and center.Results:A total of 790 TURBT procedures were analyzed.The proportion of muscle-invasive bladder cancer(pT≥2)declined over time(18.7%in 2019 to 13.2%in 2022;p=0.63),while superficial tumors(pTa)increased(57.2%to 65.5%).All-cause mortality significantly decreased from 38.0%in 2019 to 22.0%in 2020,20.5%in 2021,and 19.5%in 2022(p=0.006).EAPC showed a significant annual decline in mortality(–24.3%,p=0.004).In multivariable analysis,2020,2021,and 2022 were each associated with significantly lower odds of mortality compared to 2019.Recurrence rates remained stable across all periods(p=0.93).Interhospital variation persisted in mortality and recurrence.Conclusions:Despite the pandemic,urothelial bladder cancer outcomes did not worsen through 2022.On the contrary,timely reorganization,prioritization of TURBT,and triage strategies were associated with reduced mortality and palliative care needs,highlighting the resilience of cancer care when guided by adaptive health policies.展开更多
SnSe is a promising thermoelectric(TE) compound that has attracted increasing attention in recent years,highlighting its advantages in wide temperature range applications.Nanocomposite material engineering provides a ...SnSe is a promising thermoelectric(TE) compound that has attracted increasing attention in recent years,highlighting its advantages in wide temperature range applications.Nanocomposite material engineering provides a straightforward and practical approach to enhance the TE transport performance and mechanical strength of materials.In this study,SiC nanoparticles with varying mass percentages were incorporated into cubic SnSe-based TE materials using the wet ball milling method via mechanical activation(MA).During the rapid hotpressing sintering(HPS) process,the SiC nanoparticles dispersed at the matrix interface and effectively hindered grains growth owing to the pinning effect.The refined grains and multiple interfaces improved the hole carrier concentration(n) and enhanced the phonon scattering,which collectively optimized the electrical and thermal transport properties of cubic SnSe-based nanocomposites,thereby significantly improving the TE dimensionless figure of merit(ZT).Eventually,the sample with 1.25 wt%SiC achieved the highest ZT of ~1.14 at 750 K,which was twice that of the uncomposite sample.In terms of mechanical properties,the addition of SiC nanoparticles can effectively enhance the Vickers hardness(H_(v)) of the material,further demonstrating that this work offers an effective strategy for improving the performance of cubic SnSe-based TE materials.展开更多
The rock-salt cubic SnSe compound with multiple valleys and inherent low thermal conductivity is considered to be a promising thermoelectric compound.In this study,heterogeneous Pb atoms were strategically introduced ...The rock-salt cubic SnSe compound with multiple valleys and inherent low thermal conductivity is considered to be a promising thermoelectric compound.In this study,heterogeneous Pb atoms were strategically introduced into the lattice of cubic SnSe matrix,synergistically adjusting the thermoelectric transport properties of samples by optimizing hole carrier concentration(n)and suppressing thermal conductivity(κ_(tot)).When the doping content reached 0.08 mol,the peak power factor(PF)at 300 K increased to 20.00μW·cm^(-1)·K^(-2).The growing internal microstrain induced by the differences in atomic size strengthened the phonon scattering and effectively reduced the lattice thermal conductivity(κ_(L)).With further decoupling of the electrical and thermal transport properties,a peak thermoelectric figure of merit(ZT)of 0.82 and an average ZT of 0.42(300-750 K)were achieved in the samples doped with 0.10 mol Pb.These findings highlight the effectiveness of the selected dopants and demonstrate their synergy in improving the performance of thermoelectric materials.展开更多
It was long accepted that the microgranular structure of many Ferralsols was mainly related to physicochemical processes and to their mineralogical composition. It now appears, however, that this microgranular structu...It was long accepted that the microgranular structure of many Ferralsols was mainly related to physicochemical processes and to their mineralogical composition. It now appears, however, that this microgranular structure originates from the burrowing activity of termites and ants. Given its importance for the physical properties of Ferralsols, it will be necessary to study the different termite and ant species responsible for this microgranular structure and the characteristics of the burrowing activity associated with species.展开更多
Recently,numerous estimation issues have been solved due to the developments in data-driven artificial neural networks(ANN)and graph neural networks(GNN).The primary limitation of previous methodologies has been the d...Recently,numerous estimation issues have been solved due to the developments in data-driven artificial neural networks(ANN)and graph neural networks(GNN).The primary limitation of previous methodologies has been the dependence on data that can be structured in a grid format.However,physiological recordings often exhibit irregular and unordered patterns,posing a significant challenge in conceptualising them as matrices.As a result,GNNs which comprise interactive nodes connected by edges whose weights are defined by anatomical junctions or temporal relationships have received a lot of consideration by leveraging implicit data that exists in a biological system.Additionally,our study incorporates a structural GNN to effectively differentiate between different degrees of infection in both the left and right hemispheres of the brain.Subsequently,demographic data are included,and a multi-task learning architecture is devised,integrating classification and regression tasks.The trials used an authentic dataset,including 800 brain x-ray pictures,consisting of 560 instances classified as moderate cases and 240 instances classified as severe cases.Based on empirical evidence,our methodology demonstrates superior performance in classification,surpassing other comparison methods with a notable achievement of 92.27%in terms of area under the curve as well as a correlation coefficient of 0.62.展开更多
Marine biological activity has long been recognized to impact the atmospheric chemistry of coastal areas.In this work,we monitored the seasonal variation of carbonyl compounds in the coastal city of Qingdao,located in...Marine biological activity has long been recognized to impact the atmospheric chemistry of coastal areas.In this work,we monitored the seasonal variation of carbonyl compounds in the coastal city of Qingdao,located in the north of China’s coastline and the south of Jiaodong Peninsula,with the vast hinterland in the west.The mean total concentration of the 15 carbonyls varied significantly between seasons,with the highest observed in autumn(10.2±6.2 ppbv),followed by spring(9.0±3.0 ppbv),winter(6.4±4.0 ppbv)and summer(3.4±1.4 ppbv).Using bivariate analysis,the agricultural emissions from inland areas were responsible for the high levels of carbonyls in the autumn.In summer,clean and humid sea winds helped reduce the concentration of carbonyls,but they also brought air masses from vegetation,and marine organisms,which contributed to high levels of carbonyls in the spring of coastal areas.The observation-based chemistry box model found that the forma-tion of formaldehyde and acetaldehyde was primarily controlled by the RO+O2 reaction,and alkenes oxidation was the main contributing factor.Based on the OH radical loss rate(LOH)and ozone formation potential(OFP)calculation,we found that autumn and spring seasons have significantly higher values of LOH and OFP than winter and summer due to the presence of high concentrations of carbonyl compounds.Therefore,it is believed that these carbonyl compounds primarily originate from agricultural activities,and marine air influences the atmospheric chemistry of the coastal areas.展开更多
The Tianshan range could have been built by both late Early Paleozoicaccretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug-Weiya suture ismarked by Ordovician ophiolitic melange and a Silu...The Tianshan range could have been built by both late Early Paleozoicaccretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug-Weiya suture ismarked by Ordovician ophiolitic melange and a Silurian flysch sequence, high-pressure metamorphicrelics, and mylonitized rocks. The Central Tianshan belt could principally be an Ordovician volcanicarc; whereas the South Tianshan belt, a back-arc basin. Macro- and microstructures, along withunconformities, provide some kinematic and chronological constraints on 2-phase ductile deformation.The earlier ductile deformation occurring at ca. 400 Ma was marked by north-verging ductileshearing, yielding granulite-bearing ophiolitic melange blocks and garnet-pyroxene-facies ductiledeformation, and the later deformation, a dextral strike-slip tectonic process, occurred during theLate Carboniferous-Early Permian. Early Carboniferous molasses were deposited unconformably onpre-Carboniferous metamorphic and ductilely sheared rocks, implying the end of the early orogeny.The large-scale ductile strike-slip along the Aqqikkudug-Weiya zone was possibly caused by thesecond tectonic event, the Hercynian collision between the northern Tarim block and the southernSiberian block. Late Paleozoic granitic magmatism and superimposed structures overprinted this EarlyPaleozoic deformation belt. Results of geometric and kinematic studies suggest that the primaryframework of the Southern-Central Tianshan belt, at least the eastern part of the Tianshan belt, wasbuilt by these two phases of accretion events.展开更多
In the last few decades, the Late Paleozoic-Early Mesozoic tectonic evolution of South China has been quite controversial. The focus of debate is on both the age of ophiolites and the Late Paleozoic-Early Mesozoic geo...In the last few decades, the Late Paleozoic-Early Mesozoic tectonic evolution of South China has been quite controversial. The focus of debate is on both the age of ophiolites and the Late Paleozoic-Early Mesozoic geological and geodynamic environment. The Huaiyu Domain is located in the NE part of South China and exposes numerous significant geological features that are keys to understand the tectonics of South China. In this paper, we present some new evidence on stratigraphy, petrology and SHRIMP zircon U-Pb geochronology, and together with other geological and geochemical data available in the literature, and the following conclusions are suggested： 1） The eastern Jiangnan ophiolites belt, dated at 858±11 Ma by SHRIMP zircon U-Pb method, was generated during the Neoproterozoic, but not the Late Paleozoic; 2） The sedimentary rocks associated with these oceanic rocks do not contain radiolarians but Neoproterozoic acritarchs; 3） During Permian-Early Triassic times, the Huaiyu Domain was dominantly characterized by a shallow sea depositional environment since deep sea sediments are absent; and 4） The pre-Devonian tectonics of South China has been reworked by late polyphase tectonism through the Triassic and the Cretaceous periods. A Late Paleozoic-Early Mesozoic deep marine domain floored by oceanic crust never existed in the study area. The geochronological and structural data do not comply with a Late Paleozoic-Early Mesozoic South China Ocean.展开更多
This short review deals with soils as an important source of the greenhouse gas N2O. The production and consumption of N2O in soils mainly involve biotic processes: the anaerobic process of denitrification and the aer...This short review deals with soils as an important source of the greenhouse gas N2O. The production and consumption of N2O in soils mainly involve biotic processes: the anaerobic process of denitrification and the aerobic process of nitrification. The factors that significantly influence agricultural N2O emissions mainly concern the agricultural practices (N application rate, crop type, fertilizer type) and soil conditions (soil moisture, soil organic C content, soil pH and texture). Large variability of N2O fluxes is known to occur both at different spatial and temporal scales. Currently new techniques could help to improve the capture of the spatial variability. Continuous measurement systems with automatic chambers could also help to capture temporal variability and consequently to improve quantification of N2O emissions by soils. Some attempts for mitigating soil N2O emissions, either by modifying agricultural practices or by managing soil microbial functioning taking into account the origin of the soil N2O emission variability, are reviewed.展开更多
Ultrasonic imaging is becoming the most popular medical imaging modality,owing to the low price per examination and its safety.However,blood is a poor scatterer of ultrasound waves at clinical diagnostic transmit freq...Ultrasonic imaging is becoming the most popular medical imaging modality,owing to the low price per examination and its safety.However,blood is a poor scatterer of ultrasound waves at clinical diagnostic transmit frequencies.For perfusion imaging,markers have been designed to enhance the contrast in B-mode imaging.These so-called ultrasound contrast agents consist of microscopically small gas bubbles encapsulated in biodegradable shells.In this review,the physical principles of ultrasound contrast agent microbubble behavior and their adjustment for drug delivery including sonoporation are described.Furthermore,an outline of clinical imaging applications of contrast-enhanced ultrasound is given.It is a challenging task to quantify and predict which bubble phenomenon occurs under which acoustic condition,and how these phenomena may be utilized in ultrasonic imaging.Aided by high-speed photography,our improved understanding of encapsulated microbubble behavior will lead to more sophisticated detection and delivery techniques.More sophisticated methods use quantitative approaches to measure the amount and the time course of bolus or reperfusion curves,and have shown great promise in revealing effective tumor responses to anti-angiogenic drugs in humans before tumor shrinkage occurs.These are beginning to be accepted into clinical practice.In the long term,targeted microbubbles for molecular imaging and eventually for directed anti-tumor therapy are expected to be tested.展开更多
文摘Background:The COVID-19 pandemic disrupted healthcare systems globally,raising concerns about delayed cancer diagnosis and treatment.In France,transurethral resection of bladder tumors(TURBT)was prioritized in national urology guidelines to ensure the timely management of urothelial carcinoma.This study aimed to assess the impact of care reorganization on tumor staging,recurrence,palliative care,and mortality in bladder cancer patients from the pre-pandemic through late-pandemic periods.Methods:We conducted a retrospective multicenter study including all patients who underwent TURBT with histologically confirmed urothelial carcinoma between April and December of 2019(pre-pandemic),2020(early pandemic),2021(mid-pandemic),and 2022(late pandemic)in two French institutions.TURBT indications were categorized as diagnostic,palliative,or staging.Clinical and pathological data were compared across the four periods.Statistical analyses included Chi-square tests,Estimated Annual Percentage Change(EAPC),and multivariable logistic regression adjusted for age,sex,ASA score,and center.Results:A total of 790 TURBT procedures were analyzed.The proportion of muscle-invasive bladder cancer(pT≥2)declined over time(18.7%in 2019 to 13.2%in 2022;p=0.63),while superficial tumors(pTa)increased(57.2%to 65.5%).All-cause mortality significantly decreased from 38.0%in 2019 to 22.0%in 2020,20.5%in 2021,and 19.5%in 2022(p=0.006).EAPC showed a significant annual decline in mortality(–24.3%,p=0.004).In multivariable analysis,2020,2021,and 2022 were each associated with significantly lower odds of mortality compared to 2019.Recurrence rates remained stable across all periods(p=0.93).Interhospital variation persisted in mortality and recurrence.Conclusions:Despite the pandemic,urothelial bladder cancer outcomes did not worsen through 2022.On the contrary,timely reorganization,prioritization of TURBT,and triage strategies were associated with reduced mortality and palliative care needs,highlighting the resilience of cancer care when guided by adaptive health policies.
基金financially supported by Taishan Scholar Program of Shandong Province(No.tsqn202306225)Shandong Postdoctoral Science Foundation(SDBX2023025)+2 种基金the leader of scientific research studio program of Jinan(grant no.2021GXRC082)the University of Jinan Disciplinary Cross-Convergence Construction Projects 2023(Nos.XKJC-202301 and XKJC-202311)Jinan City-School Integration Development Strategy Project(No.JNSX2023015 and No.JNSX2023018)
文摘SnSe is a promising thermoelectric(TE) compound that has attracted increasing attention in recent years,highlighting its advantages in wide temperature range applications.Nanocomposite material engineering provides a straightforward and practical approach to enhance the TE transport performance and mechanical strength of materials.In this study,SiC nanoparticles with varying mass percentages were incorporated into cubic SnSe-based TE materials using the wet ball milling method via mechanical activation(MA).During the rapid hotpressing sintering(HPS) process,the SiC nanoparticles dispersed at the matrix interface and effectively hindered grains growth owing to the pinning effect.The refined grains and multiple interfaces improved the hole carrier concentration(n) and enhanced the phonon scattering,which collectively optimized the electrical and thermal transport properties of cubic SnSe-based nanocomposites,thereby significantly improving the TE dimensionless figure of merit(ZT).Eventually,the sample with 1.25 wt%SiC achieved the highest ZT of ~1.14 at 750 K,which was twice that of the uncomposite sample.In terms of mechanical properties,the addition of SiC nanoparticles can effectively enhance the Vickers hardness(H_(v)) of the material,further demonstrating that this work offers an effective strategy for improving the performance of cubic SnSe-based TE materials.
基金supported by Taishan Scholar Program of Shandong Province(No.tsqn202306225)Shandong Postdoctoral Science Foundation(SDBX2023025)+2 种基金Leader of Scientific Research Studio Program of Jinan(No.2021GXRC082)University of Jinan Disciplinary Cross-Convergence Construction Projects 2023(Nos.XKJC-202301 and XKJC-202311)Jinan City-School Integration Development Strategy Project(Nos.JNSX2023015 and JNSX2023018).
文摘The rock-salt cubic SnSe compound with multiple valleys and inherent low thermal conductivity is considered to be a promising thermoelectric compound.In this study,heterogeneous Pb atoms were strategically introduced into the lattice of cubic SnSe matrix,synergistically adjusting the thermoelectric transport properties of samples by optimizing hole carrier concentration(n)and suppressing thermal conductivity(κ_(tot)).When the doping content reached 0.08 mol,the peak power factor(PF)at 300 K increased to 20.00μW·cm^(-1)·K^(-2).The growing internal microstrain induced by the differences in atomic size strengthened the phonon scattering and effectively reduced the lattice thermal conductivity(κ_(L)).With further decoupling of the electrical and thermal transport properties,a peak thermoelectric figure of merit(ZT)of 0.82 and an average ZT of 0.42(300-750 K)were achieved in the samples doped with 0.10 mol Pb.These findings highlight the effectiveness of the selected dopants and demonstrate their synergy in improving the performance of thermoelectric materials.
基金financial support from the LabEx VOLTAIRE (ANR-10-LABX-100-01)the EquipEx PLANEX (ANR-11-EQPX-0036) projects。
文摘It was long accepted that the microgranular structure of many Ferralsols was mainly related to physicochemical processes and to their mineralogical composition. It now appears, however, that this microgranular structure originates from the burrowing activity of termites and ants. Given its importance for the physical properties of Ferralsols, it will be necessary to study the different termite and ant species responsible for this microgranular structure and the characteristics of the burrowing activity associated with species.
文摘Recently,numerous estimation issues have been solved due to the developments in data-driven artificial neural networks(ANN)and graph neural networks(GNN).The primary limitation of previous methodologies has been the dependence on data that can be structured in a grid format.However,physiological recordings often exhibit irregular and unordered patterns,posing a significant challenge in conceptualising them as matrices.As a result,GNNs which comprise interactive nodes connected by edges whose weights are defined by anatomical junctions or temporal relationships have received a lot of consideration by leveraging implicit data that exists in a biological system.Additionally,our study incorporates a structural GNN to effectively differentiate between different degrees of infection in both the left and right hemispheres of the brain.Subsequently,demographic data are included,and a multi-task learning architecture is devised,integrating classification and regression tasks.The trials used an authentic dataset,including 800 brain x-ray pictures,consisting of 560 instances classified as moderate cases and 240 instances classified as severe cases.Based on empirical evidence,our methodology demonstrates superior performance in classification,surpassing other comparison methods with a notable achievement of 92.27%in terms of area under the curve as well as a correlation coefficient of 0.62.
基金supported by the National Natural Science Foundation of China(Nos.21976106,42005092,and 42105111)the Natural Science Foundation of Shandong Province(Nos.ZR2020QD058 and ZR2021QD144)+1 种基金the Introduction and Cultivation Plan for Young Innovative Talents of Colleges and Universities by the Education Department of Shandong Province(No.142,2019)。
文摘Marine biological activity has long been recognized to impact the atmospheric chemistry of coastal areas.In this work,we monitored the seasonal variation of carbonyl compounds in the coastal city of Qingdao,located in the north of China’s coastline and the south of Jiaodong Peninsula,with the vast hinterland in the west.The mean total concentration of the 15 carbonyls varied significantly between seasons,with the highest observed in autumn(10.2±6.2 ppbv),followed by spring(9.0±3.0 ppbv),winter(6.4±4.0 ppbv)and summer(3.4±1.4 ppbv).Using bivariate analysis,the agricultural emissions from inland areas were responsible for the high levels of carbonyls in the autumn.In summer,clean and humid sea winds helped reduce the concentration of carbonyls,but they also brought air masses from vegetation,and marine organisms,which contributed to high levels of carbonyls in the spring of coastal areas.The observation-based chemistry box model found that the forma-tion of formaldehyde and acetaldehyde was primarily controlled by the RO+O2 reaction,and alkenes oxidation was the main contributing factor.Based on the OH radical loss rate(LOH)and ozone formation potential(OFP)calculation,we found that autumn and spring seasons have significantly higher values of LOH and OFP than winter and summer due to the presence of high concentrations of carbonyl compounds.Therefore,it is believed that these carbonyl compounds primarily originate from agricultural activities,and marine air influences the atmospheric chemistry of the coastal areas.
基金the supports from the National 973 Project on Westemn China (No.2001CB409804)the National Natural Science Foundation of China (grants 49772151 , 49832040)
文摘The Tianshan range could have been built by both late Early Paleozoicaccretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug-Weiya suture ismarked by Ordovician ophiolitic melange and a Silurian flysch sequence, high-pressure metamorphicrelics, and mylonitized rocks. The Central Tianshan belt could principally be an Ordovician volcanicarc; whereas the South Tianshan belt, a back-arc basin. Macro- and microstructures, along withunconformities, provide some kinematic and chronological constraints on 2-phase ductile deformation.The earlier ductile deformation occurring at ca. 400 Ma was marked by north-verging ductileshearing, yielding granulite-bearing ophiolitic melange blocks and garnet-pyroxene-facies ductiledeformation, and the later deformation, a dextral strike-slip tectonic process, occurred during theLate Carboniferous-Early Permian. Early Carboniferous molasses were deposited unconformably onpre-Carboniferous metamorphic and ductilely sheared rocks, implying the end of the early orogeny.The large-scale ductile strike-slip along the Aqqikkudug-Weiya zone was possibly caused by thesecond tectonic event, the Hercynian collision between the northern Tarim block and the southernSiberian block. Late Paleozoic granitic magmatism and superimposed structures overprinted this EarlyPaleozoic deformation belt. Results of geometric and kinematic studies suggest that the primaryframework of the Southern-Central Tianshan belt, at least the eastern part of the Tianshan belt, wasbuilt by these two phases of accretion events.
基金This study is financially supported by grants from the National Natural Science Foundation of China （grant nos. 40221301, 40634022, and 40572118） and Ministry of Education in China （grant nos. 306007 and 20060284008）.
文摘In the last few decades, the Late Paleozoic-Early Mesozoic tectonic evolution of South China has been quite controversial. The focus of debate is on both the age of ophiolites and the Late Paleozoic-Early Mesozoic geological and geodynamic environment. The Huaiyu Domain is located in the NE part of South China and exposes numerous significant geological features that are keys to understand the tectonics of South China. In this paper, we present some new evidence on stratigraphy, petrology and SHRIMP zircon U-Pb geochronology, and together with other geological and geochemical data available in the literature, and the following conclusions are suggested： 1） The eastern Jiangnan ophiolites belt, dated at 858±11 Ma by SHRIMP zircon U-Pb method, was generated during the Neoproterozoic, but not the Late Paleozoic; 2） The sedimentary rocks associated with these oceanic rocks do not contain radiolarians but Neoproterozoic acritarchs; 3） During Permian-Early Triassic times, the Huaiyu Domain was dominantly characterized by a shallow sea depositional environment since deep sea sediments are absent; and 4） The pre-Devonian tectonics of South China has been reworked by late polyphase tectonism through the Triassic and the Cretaceous periods. A Late Paleozoic-Early Mesozoic deep marine domain floored by oceanic crust never existed in the study area. The geochronological and structural data do not comply with a Late Paleozoic-Early Mesozoic South China Ocean.
基金Supported by the Region Centre, the Fonds Européen de Développement Régional and the INRA, France, through the SpatioFlux Program
文摘This short review deals with soils as an important source of the greenhouse gas N2O. The production and consumption of N2O in soils mainly involve biotic processes: the anaerobic process of denitrification and the aerobic process of nitrification. The factors that significantly influence agricultural N2O emissions mainly concern the agricultural practices (N application rate, crop type, fertilizer type) and soil conditions (soil moisture, soil organic C content, soil pH and texture). Large variability of N2O fluxes is known to occur both at different spatial and temporal scales. Currently new techniques could help to improve the capture of the spatial variability. Continuous measurement systems with automatic chambers could also help to capture temporal variability and consequently to improve quantification of N2O emissions by soils. Some attempts for mitigating soil N2O emissions, either by modifying agricultural practices or by managing soil microbial functioning taking into account the origin of the soil N2O emission variability, are reviewed.
文摘Ultrasonic imaging is becoming the most popular medical imaging modality,owing to the low price per examination and its safety.However,blood is a poor scatterer of ultrasound waves at clinical diagnostic transmit frequencies.For perfusion imaging,markers have been designed to enhance the contrast in B-mode imaging.These so-called ultrasound contrast agents consist of microscopically small gas bubbles encapsulated in biodegradable shells.In this review,the physical principles of ultrasound contrast agent microbubble behavior and their adjustment for drug delivery including sonoporation are described.Furthermore,an outline of clinical imaging applications of contrast-enhanced ultrasound is given.It is a challenging task to quantify and predict which bubble phenomenon occurs under which acoustic condition,and how these phenomena may be utilized in ultrasonic imaging.Aided by high-speed photography,our improved understanding of encapsulated microbubble behavior will lead to more sophisticated detection and delivery techniques.More sophisticated methods use quantitative approaches to measure the amount and the time course of bolus or reperfusion curves,and have shown great promise in revealing effective tumor responses to anti-angiogenic drugs in humans before tumor shrinkage occurs.These are beginning to be accepted into clinical practice.In the long term,targeted microbubbles for molecular imaging and eventually for directed anti-tumor therapy are expected to be tested.
